ICHTHYOMENIA POROSA. 163 



side a very large seminal receptacle is attached. Each originates as a slender 

 duct, which pui'sues a tortuous course anteriorly, and opens on the lateral or 

 latero-ventral surface of a vesicular enlargement with folded walls. The cells 

 composing the duct are histologically essentially the same as those of the seminal 

 vesicles save that they are of almost twice the height. Those of the dilation are 

 likewise columnar and contain a glandular secretion which escapes distally in 

 the form of moderately staining droplets. In addition to this secretion the 

 receptacle contains numbers of sperms some of which are deeply imbedded in 

 the walls. Whether these last named structures are intact or not it is im- 

 possible to state; they show no clear signs of disintegration. 



The Y-shaped ventral section, or shell gland, is of large size and its walls, 

 developed into many irregular folds, are unusually thin. Distal to the median, 

 undivided section the cells of the epithelial lining are chiefly glandular, hemmed 

 in by slender supporting cells, and are filletl with a violet colored vacuolated 

 secretion in haematoxylin preparations. In the adjacent undivided region this 

 type of cell is replaced by another of much greater length (Plate 24, fig. 2) in 

 which the secretion is more vacuolated and stains less deeply. Associated with 

 these are comparatively few elongated cells filled with a dark, coarsely granular 

 secretion and very many containing in each a granule of a dark brownish color. 

 These occur in the anterior half of the undivided part of the shell gland; from 

 it the transition to the posterior half is very abrupt, especially dorsally where 

 the cells become higher and are filled almost completely with a substance of 

 varying character, depending probably on the nearness of the egg-laying season. 

 In one specimen with sex products in the pericardial cavity these cells near their 

 free surface contain one or two large spherical dark blue or violet globules, 

 while the remaining cytoplasm, is packed with an almost homogeneous mass. 

 Ventrally the secretion is more granular and -the more distal products are yellow- 

 ish brown in color. In another specimen treated in identically the same manner 

 these products have much the same appearance, but stain slightly. The lumen 

 of the shell gland is spacious and opens in the dorsal part of the cloacal cavity 

 near the anus. 



Opening by a wide pore jiosterior to the rejiroductive outlet is a large diver- 

 ticulum of unknown function (Plate 6, fig. 1). Its walls are somewhat folded 

 and are reinforced by a thick muscular coat (Plate 24, fig. 2). The epithelial 

 lining consists of columnar cells of average height covered externally with a thin, 

 sharply defined cuticular layer. Among the cells of this character are others, 

 fairly numerous, very slender, with dense elongate nuclei, that in especially 



